Is sugar a hydrocarbon

Dextrose = glucose - a carbohydrate

Discovery of grape sugar

In chemistry, grape sugar is called glucose. Glucose is found not only in grapes, but also in other ripe fruits. In 1792 it was discovered by Johann Tobias Lowitz, who also recognized that glucose is something different from cane sugar (sucrose).

In 1838, Jean Baptiste Dumas coined the term glucose, which eventually became established in the chemical literature.

If you examine glucose chemically, it turns out that it is made up of carbon, hydrogen and oxygen. Two hydrogen atoms and one oxygen atom meet a carbon atom - the ratio of the number of atoms is thus:

$ \ mathrm {C \: \ H \: \ O \ = \ 1 \: \ 2 \: \ 1} $

Experiment 2 confirms that hydrogen and oxygen are present in the same ratio as in water, because conc. Sulfuric acid removes water from the glucose, so that carbon remains as a black mass.

It used to be wrongly thought that a water molecule was bound to each carbon atom like a hydrate, which is why Carl Schmidt coined the term carbohydrates in 1844. The chemical names of the individual carbohydrates end with -eyelet.

With the knowledge that in carbohydrates (also called saccharides) the general formula Cn(H2O)n predominates, but the molecular formula of glucose was by no means clarified, because CH2O or C2H4O2 correspond to this ratio. The solution is found by determining the molecular mass of the glucose. It is 180 and therefore the empirical formula is:

$ \ mathrm {C_6H_ {12} O_6} $ or $ \ mathrm {C_6 {(H_2O)} _ 6} $

Finally, if one wants to establish a structural formula, one must first be clear about the functional groups of glucose.

Detection of the functional groups

The sweet taste and the good solubility in water (see Glycerin, Chapter 99) as well as the positive outcome of the Tollensprobe can be explained by the presence of hydroxyl groups in the sugar molecule. This leads to the question of whether the glucose is possibly a polyhydric alcohol. This contradicts experiment 5, in which the hexahydric alcohol mannitol shows no reaction with the Fehling's sample.

Since glucose reacts positively with Fehling, there must also be an aldehyde group. Careful investigations revealed that the glucose molecule contains 5 hydroxyl groups and 1 aldehyde group. The following structure can be established from this:

$ \ mathrm {CH_2OH \ - \ CHOH \ - \ CHOH \ - \ CHOH \ - \ CHOH \ - \ \! \! \! \! \! \! \! \! \! \! \! \! \! \! {\ overset {\ qquad \ qquad {\ Large O}} {\ overset {\ qquad \ \ diagup \! \! \ diagup} {\ underset {\ qquad \ qquad {\ Large H}} {\ underset {\ qquad \ diagdown} C}}}}} $
Grape sugar (glucose)

A seemingly contradicting observation

The Schiff's test (Chapter 101), which is positive for aldehydes, fails for glucose, although this sugar also contains an aldehyde group. Chemists can explain this initially contradicting observation by assuming a ring structure of the glucose molecule:

The ring structure is in equilibrium with the aldehyde form, which is so strongly shifted to the side of the ring molecules that some aldehyde reactions do not occur with the glucose.

Glucose - an essential sugar


For most organisms it is glucose the Fuel molecule in general - it is mainly produced by plants using photosynthesis from sunlight, water and carbon dioxide. Glucose is the most biologically important and most common sugar. When they are oxidized, a large amount of energy is released:

$ \ mathrm {C_6H_ {12} O_6 + 6 \ O_2 \ \ longrightarrow \ 6 \ CO_2 + 6 \ H_2O + 2824 \ kJ} $

Normally, glucose only occurs in the form of its polymers, for example lactose, beet sugar, starch, cellulose and others. Along with fructose, glucose is the most important sugar in the metabolism. Both are energy carriers and also serve as cell building blocks.

Blood sugar

The glucose in the blood is called blood sugar. With diabetes, the body produces too little or no insulin, a hormone that regulates blood sugar levels. In a healthy person this is always around 0.1%. Without insulin, no glucose can be transported in the cells, which is why the sugar content in the blood increases.

In the case of threatening exhaustion or inflammation of the heart muscle, the doctor injects glucose solution into the blood. As dextropur, grape sugar is available in chemically pure form; In addition to glucose, Dextro Energy also contains fruit acids.